We are a part of him

God is our creator
God is our father.
We are God's children.
Doesn't this mean "we are a part of him "? And this sentence cannot be written in more simpler words !
"We are a part of him "
So let me know where is the confusion?
Why do
people slay people out of respect to God,
People harm people out of respect to God if they themselves are a part of him?
If you can't respect a part of God how do you even think of respecting  him as a whole??